广西里湖地下河水化学特征及其影响因素

Hydrochemical Feature and Its Influencing Factors of Lihu Underground Water,Guangxi

关键词:  水化学特征  岩溶地下河  人类活动  自净作用

Key words:  hydrochemistry  karst underground water  human action  self-purification

摘要:

[目的]岩溶地下水由于储量相对丰富，水质优良，是良好的供水水源。因此，揭示岩溶地下水水化学特征及其影响因素，能够为保护和利用岩溶地下水提供科学依据。[方法]以广西里湖地下河为研究对象，于不同季节对里湖地下河上游到下游的河水进行水化学分析。[结果]里湖地下河水主要阴离子为HCO₃^-，主要阳离子为Ca²⁺，水化学类型为HCO₃-Ca型，影响水质变化的主要离子为Cl^-，NO₃^-，SO₄^2-；各离子浓度从上游到下游变化不一致，总体呈现先升高再降低的趋势，季节变化体现在雨季离子浓度偏低，旱季偏高。[结论]地下水地球化学组成受控于碳酸盐岩的自然风化溶解；污染物质主要来源于人类活动的输入，降雨的稀释作用是影响水质季节性变化的主要原因，地下河自身存在的自净能力使得污染物浓度降低，尤其是甘田坝到小龙洞洞穴伏流段水体中部分污染物的浓度显著降低。

Abstract:

[Objective] Karst groundwater has been considered as an important source of water supply because of the relatively abundance and excellent quality. Therefore,revealing the hydrochemistry features of karst groundwater and its influencing factors can provide a scientific basis for the protection and utilization of karst groundwater.[Methods] Taking the underground lake of Lihu in Guangxi as the research object,the water chemical analysis was carried out on the upstream and downstream rivers of the Lihu underground river in different seasons.[Results] The main anion in the underground water of Lihu Lake is HCO₃^-,the cation is Ca²⁺,and the hydrochemistry type is HCO₃-Ca. The main ions affecting the change of water quality are Cl^-,NO₃^-,SO₄^2-. The variation of each ion concentration from upstream to downstream is inconsistent,and the overall trend is to increase first and then decrease. The seasonal variation is reflected in that the ion concentration is lower in rainy season and higher in dry season.[Conclusion] The hydrochemistry composition of groundwater is controlled by the natural weathering and dissolution of carbonate rocks. Contaminants are mainly derived from the input of human activities,and the dilution of rainfall is the main cause of seasonal changes in water quality. Moreover,the self-purification ability of the underground river itself reduces the concentration of pollutants. In particular,the concentration of some pollutants in the water body of the cavern from the Gantianba to Xiaolongdong caverns was significantly reduced.